The Montgomery bus boycott lasted 381 days, from December 5, 1955, to December 20, 1956.
The protest began after Rosa Parks was arrested for refusing to give up her seat on a segregated Montgomery bus. Black residents organized carpools and avoided the city buses, creating severe financial pressure on Montgomery’s bus system.
The boycott ended after the U.S. Supreme Court’s decision in Browder v. Gayle was implemented. That ruling found Alabama’s bus segregation laws unconstitutional. Martin Luther King Jr., then a young Montgomery minister, became a prominent boycott leader.
The boycott is sometimes described as lasting “about a year,” but 381 days is the specific historical figure. It became a major early victory for the modern U.S. civil rights movement.